I really like the headcanon that the Urameshis are descended from the burakumin group1, which explains why Yuusuke's teachers seem to hate him and his mom so disproportionately, even for a single alcoholic mother and her delinquent son. Atsuko also has ties to the Yakuza (more in the manga than the anime, which sort of glosses over it) which also makes sense with this idea, since burakamin make up about 60% of the Yakuza (due to difficulty getting better work). Yuusuke (and probably Atsuko, since it's never clarified which side of the family Raizen is on but she does have sensory powers so I'd guess Raizen is her ancestor as well) is also canonically descended from a woman who ingested corpses to provide medical services, which would again contribute to her descendants eventually being considered burakumin.